﻿/**
 * 
 * Copyright 2009, 2010 Mike Jamer [email: mikejamer@gmail.com ]
 * 
 * This File is part of Moose IRC
 * 
 * MooseIRC is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * MooseIRC is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with MooseIRC.  If not, see <http://www.gnu.org/licenses/>.
 * 
 */

using System;
using System.Collections.Generic;
using moose.irc.extension;

namespace moose.irc {
    /// <summary>
    /// IRC Action, executes bits of code, in response to triggers, or 
    /// as extensions to other actions 
    /// </summary>
    [CLSCompliant(true)]
    public abstract class IrcAction : object {

        /// <summary>
        /// A really basic, linear hierarchy,
        /// this enables overriding actions, and enables an override to invoke the base
        /// action
        /// </summary>
        internal LinkedList<IrcAction> m_llObjectHierarchy;

        /// <summary>
        /// Initialize IrcAction 
        /// </summary>
        public IrcAction()
            : base() {
            initialize(this);
            return;
        }

        /// <summary>
        /// No need to build hierarchy nessecarily 
        /// </summary>
        /// <param name="owner">
        /// A <see cref="IrcAction"/>
        /// </param>
        public IrcAction(IrcAction owner)
            : base() {
            initialize(owner);
            return;
        }

        private void initialize(IrcAction owner) {
            if (owner.m_llObjectHierarchy == null) //This will either be the root
                owner.m_llObjectHierarchy = new LinkedList<IrcAction>();
            else //or an extension
                m_llObjectHierarchy = owner.m_llObjectHierarchy;

            m_llObjectHierarchy.AddLast(this);

            if (owner == this) //This is root, lets build the object hierarchy
                build_object_hierarchy();

            return;
        }

        /// <summary>
        /// Returns valid Session States for action to execute 
        /// </summary>
        /// <returns>
        /// A <see cref="IrcSessionStates"/>,
        /// bitwise stacked value, indicating all possible states for this action 
        /// to execute.
        /// Any other current state, will throw an exception instead.
        /// </returns>
        public abstract IrcSessionStates valid_states();

        /// <summary>
        /// must override this, 
        /// this is the actual action, whatever the command / response is supposed to do...
        /// </summary>
        /// <param name="session">
        /// A <see cref="IrcSession"/>
        /// </param>
        /// <param name="message">
        /// A <see cref="IrcMessage"/>
        /// </param>
        public abstract void action(IrcSession session, IrcMessage message);

        /// <summary>
        /// Execute the base Action Logic 
        /// </summary>
        /// <param name="session">
        /// A <see cref="IrcSession"/>
        /// </param>
        /// <param name="message">
        /// A <see cref="IrcMessage"/>
        /// </param>
        protected void base_action(IrcSession session, IrcMessage message) {
            //If this is the parent, there is nothing to invoke.  We will short circuit quietly, no need to make a fuss
            if (m_llObjectHierarchy.First.Value == this) return;
            m_llObjectHierarchy.Find(this).Previous.Value.action(session, message);
            return;
        }

        /// <summary>
        /// Execute IRC Action 
        /// </summary>
        /// <param name="session">
        /// A <see cref="IrcSession"/>
        /// </param>
        /// <param name="message">
        /// A <see cref="IrcMessage"/>
        /// </param>
        public void execute(IrcSession session, IrcMessage message) {
            IrcAction action = m_llObjectHierarchy.Last.Value;
            if ((action.valid_states() & session.SessionState) != session.SessionState)
                return; //Will not execute in case of incorrect session state
            action.action(session, message);
            return;
        }

        /// <summary>
        /// Builds Object Heirarchy 
        /// </summary>
        private void build_object_hierarchy() {

            IrcAction extension = ExtensionManager.get_extension(this.GetType(), this);
            while (extension != null) {
                extension = ExtensionManager.get_extension(extension.GetType(), extension);
            }

            return;
        }

    }
}
